1. Field of Invention
The present invention relates to a method for separating metal and inorganic particles from a metal-inorganic particle composite material generated because of dispersion of inorganic particles in base metal.
2. Related Art
Metal-inorganic particle composite materials generated by dispersing inorganic particles in base metal have been used widely for various kinds of members for the purpose of reduction in material weight, improvement in mechanical strength, and provision of functionality. However, waste disposal of such metal-inorganic particle composite materials have come into a problem. In the related art, there have been adopted measures such that the metal-inorganic particle composite materials are simply ground and mixed into other materials as they are, and stored or disposed of by landfills.
Further, with growing movement of environmental preservation or recycling of resources, there have been attempts to separate wastes of metal-inorganic particle composite materials into respective components and recover the components. However, in the present circumstances, no effective method is, in fact, established. For example, unexamined Japanese Patent Hei. 7-41874 discloses the following method. That is, a molten slag containing metal and inorganic particles is dry-ground into fine particles having a moderate particle size. The fine slag powder is subjected to low magnetic force selection under magnetic flux density not higher than 1,000 gauss. Thus, iron-component particles in the slag powder is selectively recovered by magnetic attraction. On the other hand, the residual slag powder after the low magnetic force selection is subjected to high magnetic force selection under magnetic flux density ranging from 1,000 gauss to 13,000 gauss. Further, aluminum-component particles or copper-component particles remaining after the high magnetic force selection are recovered individually by separation based on specific gravity.
In the method, however, it is necessary to form slag into fine powder. In addition, it is necessary to prepare a plurality of stages of magnetic force selection different in magnetic flux density, and a step of separation based on specific gravity. Thus, the process includes many steps and is complicated. Besides, the method is applicable only to metal-inorganic composite materials containing magnetic materials. Therefore, the application of the method is limited to some extent.
Oxides or nonferrous metal mediators generated at the time of manufacturing are generally mixed into metal-inorganic composite materials. However, in any method including the method described above, it is difficult to eliminate such components and separate metal therefrom. Accordingly, the purity of metal recovered is generally so low that an additional refining work may be required to use the metal as a fresh metal raw material.
The invention was developed in consideration of such complications. An object of the invention is to provide a method for separating metal and inorganic particles from a metal-inorganic particle composite material, by which high-purity metal can be recovered efficiently with a simple and easy operation regardless of the composition of the metal-inorganic particle composite material, particularly regardless of the kind of metal.
In order to attain the object, the invention provides a method for separating metal and inorganic particles from a metal-inorganic particle composite material generated because of dispersion of inorganic particles in base metal, the method including the steps of heating the metal-inorganic particle composite material into a melt; throwing flux into the melt and bringing the flux into contact with the melt sufficiently; subsequently leaving the melt at rest to thereby separate the melt into an upper layer containing the inorganic particles and a lower layer composed of the metal; and subsequently recovering the upper layer and the lower layer individually.